Scotland's First Minister, Nicola Sturgeon (R), greets Britain's new Prime Minister, Theresa May, as she arrives at Bute House in Edinburgh, Scotland, Britain July 15, 2016. Reuters LONDON — Scottish Parliament passed a motion in favour of a second independence referendum on Tuesday— but the chances of Scotland opting for independence in a second vote are only 40%, according to investment bank Berenberg.

The firm forecasts a 70% chance that Scotland will hold a fresh vote before 2020, and a 40% chance that Scotland would leave if it did.

The prime minister has the ultimate power to grant or veto any UK referendum.

The note from Berenberg said: "Since the first independence referendum, Scottish support to remain in the UK has held steady at just above 47% - the same level of poll support before the 2014 referendum that ended with 55.3% of Scottish people voting to remain.

It added: "At the current level of around 42% in opinion polls, support for independence is around 2% below the 44% shown in the pre-2014 referendum polls (support for "yes" in the 2014 referendum was 44.7%)."

"Only one in the last 17 opinion polls projects a majority of Scottish people supporting independence. A second 'no' vote would put the question to rest for at least a generation."

Take a look at the chart below, which charts poll averages for Scottish independence since December 2014:

Berenberg

While there has been an uptick in support for independence this year, support for "No" currently remains several points above support for "Yes."

May has vowed to block a second referendum until after Brexit negotiations are complete, but polling expert John Curtice told Business Insider in February that it would be " politically catastrophic" for May to permanently block a referendum, as it would risk "suggesting that Scotland cannot decide for itself whether it wishes to remain inside the Union or not."

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